The most common and most likely answer to this crossword clue is the 11 letter word TWELVE-BORE
I've seen this crossword clue in Financial Times
T
W
E
L
V
E
-
B
O
R
E
Buddy explains!
The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.